Aerospace sealants based on sulfur-containing prepolymers can meet the performance requirements of many aerospace applications. However, as existing requirements continue to develop and new requirements are imposed there is a continuing need to develop new aerospace sealants. Solvent resistance is a standard requirement for aerospace sealants. It is important that the properties of an aerospace material such as an aerospace sealant be maintained above a certain threshold and not substantially degrade following exposure to fluids that the materials can come into contact during use such as hydraulic fluid and aviation fuel. Accelerated fluid resistance tests are used to evaluate the performance of a material. One typical performed test used to evaluate fuel resistance is described, for example, in AMS 3277. In this test a material sample is immersed in Jet Reference Fluid Type I (JRF Type I), which is a mixture of organic solvents, at a temperature of 60° C. for one week. Materials that maintain properties such as tensile strength, elongation, hardness, and adhesion above an acceptable threshold following JRF Type I immersion can be considered to be fuel resistant. Another requirement that is used to qualify aerospace sealants for certain applications is resistance to phosphate ester hydraulic fluid. Resistance to phosphate ester hydraulic fluid is more difficult to achieve. For example, a sealant that passes JRF Type I fuel resistance testing can dissolve when exposed to phosphate ester hydraulic fluids at 70° C. for extended periods of time.